Alkylaromatic sulfonate detergent process of preparation

ABSTRACT

Alkylaromatic sulfonates, containing a C9-C18 linear alkyl group, are prepared by sulfonating the corresponding alkylbenzene in admixture with a C9-C18 n-paraffin and neutralizing the resultant alkylbenzene sulfonic acid, in admixture with the same paraffin, to produce a relatively colorless neutralized alkylbenzene sulfonate. This process is particularly adaptable where a C9-C18 n-paraffin stream is first converted to an alkylatable compound such as a monohalogen or mono-olefin, and such compound is not readily separable from the n-paraffin. Thus, the alkylation, sulfonation and nuetralization are all performed in admixture with the unreacted n-paraffin whereby the paraffin is readily separable from the final product, for recycle purposes.

United States Patent Bloch et al.

[451 Aug. 1,1972

Assignee:

Filed:

Appl. No.: 787,268

Inventors: Herman S. Bloch, Skokie; George E. lllingworth, ArlingtonHeights;

George W. Lester, Palatine, all of 111.

Universal Oil Products Company,

Des Plaines, 111.

Dec. 26, 1968 US. Cl. ..260/505 A, 260/683.3, 260/505 S Int. Cl ..C07c143/24 Field of Search .Q ..260/505 A, 505 S References Cited UNITEDSTATES PATENTS 3,432,567 3/1969 Jones ..260/505 A X 2,210,962 8/1940Thomas ..260/505 A 2,567,854 9/1951 Nixon ..260/505 A PrimaryExaminer-Leon Zitver Assistant Examiner-L. B. DeCrescente Attorney-JamesR. Hoatson, Jr. and Robert W. Erickson [5 7] ABSTRACT Alkylaromaticsulfonates, containing a C -C linear alkyl group, are prepared 1 bysulfonating the corresponding alkylbenzene in admixture with a C -Cnparafiin and neutralizing the resultant alkylbenzene sulfonic acid, inadmixture with the same paraffin, to produce a relatively colorlessneutralized alkylbenzene sulfonate. This process is particularlyadaptable where a C C n-paraffin stream is first converted to analkylatable compound such as a monohalogen or monoolefin, and suchcompound is not readily separable from the n-paraffin. Thus, thealkylation, sulfonation and nuetralization are all performed inadmixture with the unreacted n-paraffin whereby the paraffin is readilyseparable from the final product, for recycle purposes.

3 Claims, No Drawings BACKGROUND OF THE INVENTION This invention relatesto a process for the production of alkylaromatic sulfonates containing aC -C linear alkyl group. Generally, it is concerned with separating a C-C n-parafiin from a hydrocarbon mixture containing the paraffin,converting said paraffin to an olefin-acting compound, in particular, amonochlorinated or monobrominated paraffin, or a mono-olefin, alkylatingwith said compound, in admixture with the unconverted paraffin, amonocyclic alkylatable aromatic hydrocarbon to form an alkylaromatichydrocarbon containing a linear C C alkyl group, sulfonating saidalkylaromatic hydrocarbon and neutralizing the resultant sulfonic acid,both reactions in admixture with the unconverted paraffin, separatingfrom the neutralized product, alkylaromatic sulfonates and unconvertedn-paraffin, and recycling said paraffin to be converted into theaforementioned olefin-acting compounds. Specifically, this inventionrelates to separating the hydrocarbon phase containing the unconvertedparaffin and alkylaromatic sulfonate from the acid phase formed in thesulfonation reaction and neutralizing the hydrocarbon phase, therefromn-paraffins and neutralized sulfonic acid of excellent color quality.Further, this invention is concerned with sulfonating an alkylaromatichydrocarbon containing a C -C n-paraffin and neutralizing the resultantsulfonatein admixture with the same parafiin to provide a detergent ofexcellent color quality.

Processes for the production of biodegradable detergents have gainedconsiderable importance within the last few years because of theworld-wide ever-increasing pollution problem, stemming in part fromsewage disposal and longevity of detergents dissolved in this sewage.The presence of detergents dissolved in the sewage is the deleteriousconsequence of the inability of bacteria to degrade the originaldetergents. When these non-biodegradable detergents are aerated, such aswhen the treated sewage is discharged into rivers and lakes, largequantities of foam result. Further, the diluted detergent solutionsoften enter subsurface waters which ultimately feed into the undergroundwater strata serving many cities as a source of water supply.Occasionally, these detergents turn up in sufficient quantities in tapwater to cause the water to foam at the tap.

To meet the public s demand for pure water, which is essential to thefuture growth and development of cities and the maintenance of humanhealth standards, the petrochemical industry has attempted to solve thefoam problem in sewage disposal plants, etc. through the development ofbiodegradable detergents. It has been found that alkylaryl-baseddetergents are more readily degradable by sewage bacteria if the alkylsubstituent on the phenyl nucleus is of a simple, straight-chainconfiguration than if it is of a more complex branched chain structure.As an example, detergent compounds in which the alkyl side chain has astructure such as:

are more likely to be bacterially digested than detergents of the samechemical composition but in which recovering 1 the isomeric alkylradical is a more highly branched chain, such as:

These biodegradable detergents are generally manufactured by theisolation of C -C n-paraffins from mixtures containing the paraffinsutilizing molecular sieves or urea adduction, and converting then-paraffin to an olefin-acting compound such as a monohalogenatedparaffin or a mono-olefin, or by the cracking of saturated paraflinwaxes to produce a linear olefin. These olefin-acting compounds are thenused to alkylate a mono-cyclic aromatic such as benzene and theresultant alkylaromatic is sulfonated and neutralized to form thedesired detergent.

Complete conversion of the n-paraffin to olefin-acting compounds is notpossible because of undesired side reactions which occur in bothhalogenation and dehydrogenation reactions at high conversions,lessening the overall selectivity and yield. In addition, one of thecommon sources of C C paraffins, utilized in forming olefin-actingcompounds, are those C -C paraffins present in the kerosene fraction ofpetroleum. The n-paraffins separated from this fraction are oftenconverted to the corresponding olefin-acting compounds withoutseparating the C C, n-paraffin homologs from each other. As a result ofthe incomplete conversion to olefin-acting compounds, there results amixture of the unconverted paraffins and the resultant olefin-actingcompounds. In prior art processes, this mixture is separated into anolefin-acting compound stream and a recycle paraffin stream. However,since the reaction product contains a complex mixture of the variousolefin-acting compound isomers along with the unconverted paraffin, thisseparation is accomplished only by exotic and intricate separationtechniques. This is particularly true in the conversion of a mixture ofthe C r-C paraffin homologs to the corresponding olefin-actingcompounds. Here, there is an overlap in boiling points between theunconverted paraffins and the olefimacting compounds formed from thismixture. Present prior art processes approach this problem throughutilization of intricate separation techniques as previously mentioned,or by utilizing a narrower carbon number range in the paraffinsconverted. A further problem present in prior art processes arises inmaintaining a neutralized alkyl aromatic sulfonate free fromdiscoloration and from excessive amounts of inorganic salts such assodium sulfate. Current processes maintain their production of suchsulfonates relatively free from discoloration and excessive amounts ofinorganic salts through complex manipulation of the operating variablessuch as reaction temperature, sulfonating agent purity and strength,sulfonating agent to alkyl-aromatic ratio, reaction time, feed purity,and conversion. In addition, bleaching techniques are often employed tobring the final product up to color specifications.

SUMMARY OF THE INVENTION Accordingly, it is an object of this inventionto provide a new, improved process for the manufacture of alkyl-aromaticsulfonate detergents. Specifically, it is an object of this invention toprovide a novel means of producing alkylaromatic sulfonates containing alinear C91g alkyl group derived from the corresponding nparafiinswithout the necessity of intricate means for the separation of theunreacted paraffin. More specifically, it is an object of this inventionto provide a means for producing relatively color-free neutralizedalkylaromatic sulfonates.

In an embodiment, this invention relates to a process for producing analkylaromatic sulfonate containing a C -C linear alkyl group whichcomprises the steps of: (a) sulfonating an alkylaromatic containing a C-C linear alkyl group, in admixture with a C C n-paraftin, with asulfonating agent, to form an alkylaromatic sulfonic acid; (b)separating the resultant sulfonation mixture into an acid phase and ahydrocarbon phase containing said C -C paraffin and said sulfonic acid;(c) neutralizing said hydrocarbon phase to form a neutralizedalkylaromatic sulfonate; and, (d) separating, from the neutralizedhydrocarbon phase, said nparaffin and said neutralized aromaticsulfonate.

In a more limited embodiment, the invention relates to a process forproducing an alkylaromatic sulfonate containing a (I -C linear alkylgroup, which comprises the steps of: (a) separating a C -C n-paraffinfrom a hydrocarbon mixture containing said n-paraffin; (b) treating saidparaffin to form an olefin-acting compound such as a mono-olefin or amonochlorinated, or monobrominated paraffin, recovering the resultantolefin-acting compound in admixture with unreacted paraffin; (c)alkylating with said olefin-acting compound, in admixture with theunreacted paraffin, a monocyclic aromatic to form an alkylaromaticcontaining a C C, linear alkyl group; (d) separating from the resultantalkylated effluent, unreacted monocyclic aromatics; (e) sulfonating saidalkylaromatic in admixture with said n-paraffin with a sulfonating agentto form an alkylaromatic sulfonic acid; (f) separating the resultantsulfonation mixture into an acid phase and a hydrocarbon phasecontaining said n-paraffin and said. sulfonic acid; (g) neutralizingsaid hydrocarbon phase to form a neutralized alkylaromatic sulfonate;(h) separating, from the neutralized hydrocarbon phase, said n-paraftinand said neutralized aromatic sulfonate; and, (i) recycling at least aportion of said n-paraffin to said step (b).

In summary, a principal advantage of this invention resides in theability to produce relatively color-free alkylaromatic sulfonatescontaining a linear C -C alkyl group by sulfonating an alkylaromatic,containing said alkyl group, in admixture with (I -C n-paraffin andneutralizing the hydrocarbon phase of the sulfonation reaction. Furtheradvantages of the invention reside in the ability to convert C -Cn-parafiins to olefin-acting compounds, alkylating with such compoundsto form alkylaromatics, sulfonating the alkylaromatics and neutralizingthem, all with the reactants in admixture with unconverted n-paraffins,thus eliminating intermediate separation of the paraffin, with theability to operate over a wider carbon number range than has beenheretofore available from prior art processes.

DESCRIPTION or PREFERRED EMBODIMENTS The C C n-parafiins utilized inthis invention may be obtained from any suitable source including anappropriate fraction of a straight run petroleum distillate, typicallythose in the kerosene range; the products of the FischerTropschreaction, a process by which paraffinic hydrocarbons in the C range areformed by the reaction of hydrogen with carbon monoxide; thehydrogenated products of ethylene polymerization; and the hydrogenatedfatty acids which upon complete reduction produce parafiinichydrocarbons having a straight chain configuration. Although any sourcecontaining (I -C n-paraffins may be utilized in this invention, thepreferred source is a kerosene boiling range fraction boiling in therange from about C. to about 300 C.

All of the foregoing enumerated n-parafiin sources have a significantamount of branched chain isomers in admixture with the n-parafiins whichmust be separated if said paraffin is to be utilized in the preparationof alkylaromatic sulfonates containing a linear alkyl group. Thesen-paraffins may be separated by any of the procedures known to the art,the exact method of separation not being critical to this invention.Such separation processes include those employing molecular sievesorbents or urea adduction. The separation processes involving molecularsieves are characterized in that the zeolite structure is a crystallinealumino-silicate containing pores of about 5 Angstroms in crosssectionaldiameter which are of sufficient size to permit the entry of n-aliphaticcompounds, but are not of sufficient size to permit the entry ofbranched chain or cyclic compounds. As a result, when a mixturecontaining n-aliphatics contacts these sieves, the linear aliphaticcompounds are selectively sorbed and recovered. These separationprocesses are well known to the art, as exemplified by US. Pat. Nos.2,985,589, 3,274,099, and 3,310,486.

While the use of molecular sieves constitutes the preferred separationmeans, another separating agent applicable is urea, a compound whichforms an adduct or clathrate with straight chain compounds. Thisseparation is typically accomplished by mixing urea with a hydrocarbonfraction containing n-parafiins, thereby forming a crystalline adductwith the normal components, recovering the crystals, and freeing thenormal hydrocarbons by heating the crystals or by displacement with apreferentially sorbed compound such as an alcohol, aldehyde, or otheraliphatic compound containing a polar radical.

The recovered C -C n-paraffin may be converted by known methods to oneof the known olefin-acting compounds applicable within this invention.These compounds include olefins, alcohols, ethers, esters, the latterincluding alkyl halides, alkyl sulfates, alkyl phosphates, and esters ofcarboxylic acids, with the mono-olefins and monohalogenated paraffinsbeing preferred. The olefin-acting compound must be capable of providinga C -C straight chain alkyl group on a single aromatic nucleus, to beutilized in this invention, thus eliminating those compounds having morethan one reactive group such as polyolefins and polyhalogenatedparaffins.

Of the monohalogenated paraffins, the

monochlorinated and monobrominated are preferred. The technique ofpreparing such compounds by the halogenation of the correspondingparaffin is well known in the art, and reference thereto may be had forspecific details of the process. These halogenation techniques generallyinvolve reacting the parafiin under carefully controlled conditions toinsure monohalogenation and minimize the formation of polyhalides. Thereactions are generally carried out by contacting bromine or chlorineand excess normal parafiin. Catalytic agents, such as diffused sunlight,light of a specific wavelength, i.e., artificial ultraviolet light, ortrace amounts of iodine are often employed. The resultantmonohalogenated paraffins consist of a mixture of the various linearisomers with the internal halogenated isomers being more prevalent.

The other preferred olefin-acting compounds, the linear mono-olefins,may be derived by methods known to the art such as cracking of longchain saturated paraffms, dehydrohalogenation of the aforementionedmonohalogenated paraffins or by the selective dehydrogenation of thecorresponding linear paraffins. The selective dehydrogenation of then-paraffins yields a mixture of the corresponding internal olefinisomers and is typically effected by processes which include contactingthe n-paraffin with a dehydrogenation catalyst containing a supporthaving an alkali metal compound thereon and promoted with a metal ormetal compound selected from the metals of the the Groups VI and VIII ofthe Periodic Table. Other catalysts suitable for the dehydrogenation ofstraight chain parafiins to form straight chain mono-olefins compriserefractory spacing agents or carriers selected from the group consistingof activated alumina, magnesia, silica and diatomaceous earth, and minoramounts of the metal and/or metallic oxides of elements selected frommembers of Groups IV-B, V-B and VI-B, Group VIII, and Group [B of thePeriodic Table (E. G. Sargent & Co., 1964) and include titanium,zirconium, hafnium, and vanadium, niobium, and tantalum; chromium,molybdenum, and tungsten; iron, cobalt, nickel, platinum, palladium,copper, silver, and the like, including mixtures of the foregoing.Usually non-acidic catalysts are desirable since they minimize theamount of isomerization of the n-paraffins or resulting mono-olefins totheir branched chain isomers.

Especially preferred are those processes which contact the n-paraffinwith a catalytic composite of alkalized alumina, a Group VIII metalliccomponent, and a metallic component of arsenic, antimony, bismuth, andcompounds thereof, at dehydrogenating conditions including a temperatureof about 400 C. to about 600 C., operating pressures of about 10.0 psig.to about 100 psig., a mole ratio of hydrogen to liquid hydrocarboncharge of less than :1 and a liquid hourly space velocity above 12.0.Particularly preferred are those catalysts which are catalyticcomposites of alumina containing from about 0.01 percent to about 1.5percent by weight lithium, from about 0.05 percent to about 5.0 percentby weight of a Group VIII noble metal component and a metallic componentselected from the group consisting of arsenic, antimony, bismuth, andcompounds thereof in an atomic ratio to said Group VIII component offrom about 0.20 to about 0.50.

Typically, these dehydrogenation processes have conversions from about 5percent to about 25 percent and selectivities greater than percent.Higher conversions are possible but not practical because of undesiredside reactions which lower selectivity. The resultant dehydrogenationeffluent may be separated to recover the linear mono-olefins from theunreacted nparafiins, but since the subsequent alkylation, sulfonation,and neutralization are to take place in the presence of a C -C paraffin,it is more practical and feasible to perform these steps in the presenceof the undehydrogenated mparaffin, thus eliminating intermediateseparation. This same principle applies to those processes wherein theparafiin is first monohalogenated. Thus, the unreacted n-paraffinremaining after the formation of the olefin-acting compound is readilyrecoverable after the sulfonation and neutralization and may be recycledand converted to additional olefin-acting compound.

The aromatic reactants which are alkylated with the olefin-actingcompounds to yield a mono-alkylate include the mono-cyclic aromaticsselected from the group consisting of benzene, toluene, xylene,ethylbenzene, diethylbenzene, phenol, and mononitrobenzene. Thealkylation reaction is effected in the presence of a suitable catalystcapable of promoting the condensation reaction between the olefin-actingcompound and the monocyclic aromatic. Such catalysts are generally aninorganic material characterized as an acid-acting compound whichcatalyzes the alkyl transfer reaction involved. Such inorganic compoundsinclude certain mineral acids such as sulfuric acid containingpreferably less than 10 percent water; hydrofluoric acid of at least 83percent concentration and containing less than 10 water; liquidiedanhydrous hydrogen fluoride; anhydrous aluminum chloride or aluminumbromide; boron trifluoride, preferably utilized in admixture withconcentrated hydrofluoric acid; and other acid-acting catalysts,particularly of the Friedel-Crafts class of metal halides when theolefinacting compound is the monohalogenated paraffin. Such alkylationreaction conditions and procedures are well known to the art andreference may be made thereto for specific details. Preferred alkylationconditions include temperatures of about 20 C. to about 40 C., a molarexcess of aromatic to olefin-acting compound and a molar ratio ofcatalyst to olefin-acting compound of 0.01 or greater.

The alkylation reaction effluent is separated to recover the organicportion from the used catalyst. When utilizing a molar excess ofaromatic, the olefin is essentially completely consumed and the reactantproduct is essentially the desired mono-alkylate. The unreacted aromaticis separated from the aromatic-alkylaromatic-n-paraffin mixture, andrecycled to the alkylation reaction, by methods known to the art,including distillation and solvent extraction via sulfolane, glycol,etc. separation of the unreacted aromatic is effected to avoidsubsequent sulfonation thereof.

Sulfonation conditions include those well known to the art. The amountof n-paraffin present, the essence of this invention, is that amountrequired to remove the alkylaromatic sulfonate from the acid, leavingthe color-bodies in the acid phase. This amount typically is in therange of about 20 percent to about 96 weight percent of then-paraffin-olefin-acting compound mixture passed to the alkylation zone.This concentration includes that concentration of unconvertedn-paraffins present in the monohalogenation or dehydrogenation reactioneffluent. It is to be emphasized that the C,,C n-paraffin present in thesulfonation and neutralization steps need not be carried over from theprevious steps and may be commingled with pure alkyl-aromatic beingpassed to the sulfonation reaction.

Sulfonation conditions include a temperature of about 20 C. to about 60C. and such reactions may be conducted continuously or batchwise. Thehydrocarbon feed may be given an acid wash with sulfuric acid belowsulfonating strength to remove impurities present in the feed.Sulfonating agents which may be utilized are essentially anhydroussulfuric acid, relatively weak oleum, or even free sulfur trioxide. Suchagents are preferably used in excess of that required for completesulfonation. Specifics regarding sulfonation of alkylaromatics are wellknown to the art and may be obtained by reference thereto. An acid phasecontaining color bodies and a hydrocarbon phase containing therelatively color-free alkylaromatic sulfonic acid, are separated fromthe resulting sulfonation product.

The color bodies formed in the sulfonation reaction are the products notonly of reactions involving impurities present in the hydrocarbon feedand/or sulfonating agent but also of undesirable side reactions betweenthe principal reactants. These side reactions can be minimized but noteliminated by manipulation of operating variables. lnevitably, somecolor bodies are formed which ultimately must be removed. Since theprocess of this invention selectively removes the alkylaromaticsulfonate from the color bodies formed during sulfonation, minor upsetsin operating variables will not have as adverse an effect upon productquality as heretobefore experienced. In other words, this process is notas sensitive to operating variables which result in the inclusion ofcolor bodies in the final product, as the prior art processes.

The alkylaromatic sulfonic acids present in the hydrocarbon phaseremoved from the sulfonation reaction are neutralized to form awater-soluble alkylaromatic sulfonate detergent, preferably, with analkaline compound of potassium, sodium, lithium or magnesium with sodiumbeing especially preferred. These bases are preferably utilized inaqueous solutions and include aqueous solutions of the correspondinghydroxides and carbonates. Other basic compounds which may be utilizedin this invention include ammonia and the basic ammonium compounds andthe lower molecular weight amines. Of the neutralization conditions,temperature is the most important and should be maintained at below 70C. to avoid decomposition reactions. Other neutralization conditions andtechniques are well known to the art and reference may be had theretofor further particulars.

The neutralized sulfonic salts may be recovered by any of those methodsknown to those trained in the art including steam distillation of theneutralized mixture, spray drying, drum drying, etc. Typically, thealkylaryl sulfonate is neutralized with aqueous sodium hydroxide, thusextracting the water soluble neutralized sulfonic salt from then-paraffin phase to the aqueous phase. The resultant aqueous solution isdried by methods known to the art thereby recovering dry, inorganicsalt-free, colorless detergent. The unreacted nparaffin is readilyseparated from the final neutralization product since it forms a saltfree upper phase distinct from the aqueous lower phase. Thus, thenparaffin recovered from this step may be recycled to be admixed withthe alkylaromatic being passed to the sulfonation step, or, moretypically, back to the step wherein n-paraffins are first converted toolefin-acting compounds such as the monohalogenated paraffms ormono-olefins.

The presence of a C C n-parafiin in the alkylation, sulfonation andneutralization steps serves a multi-fold purpose. Not only does itcreate a process not requiring intermediate separation of theolefin-acting compound and its paraffin derivative, but it also providesa process more readily operable in the sulfonation step that produces arelatively color-free product. The physical presence of the paraffin inthese steps serves, first, as a heat sink for the exothermic alkylation,sulfonation, and neutralization reactions, and, secondly, as a diluentto insure uniformity within the reaction, thus rendering it moreamenable to agitation. Thirdly, the alkylaromatic sulfonic acids formedin the sulfonation reaction are removed from the acid phase into then-paraffin phase, leaving the majority of the color bodies in the acidphase. The import of this feature is obvious. First of all, the presenceof the alkylaromatic sulfonic acids formed in the sulfonation reactionwithin the n-paraffin phase reduces the amount of base necessary toneutralize the sulfonic acids heretobefore available in processeswherein the spent sulfonating and sulfonate are neutralized together;secondly, it renders a sulfonate upon neutralization free from theinorganic salt of the sulfonating agent. Most importantly, the greatmajority of the color-bodies formed within the sulfonation reactionremain in the acid phase, yielding a relatively color-free paraffinphase which upon neutralization yields a detergent with much improvedcolor characteristics than have heretobefore been available to the artother than through the use of extraneous exotic purification methods.

The process of the present invention is further described in thefollowing illustrative example which is, however, not presented for thepurpose of limiting the scope of the invention, but in order to furtherillustrate the embodiments of the present process.

EXAMPLE A straight-run petroleum fraction (recovered from a Michigancrude oil) boiling within the range of from about to about 225 C. andhaving the following composition, according to the general classes ofthe hydrocarbons present:

Wt. Percent C, C aliphatic paraffms 73 C C naphthenes 24 C C aromatics 3is resolved into the following two classes of components: (l)straight-chain or normal paraffins and (2) a mixture of isoparaffinicand cyclic hydrocarbons. The recovered normal paraffins are thereafterdehydrogenated to their mono-olefin analogs and these are thereafterused to alkylate benzene to form phenylsubstituted normal alkanes. Then-paraffin-benzene alkylate mixture is sulfonated, followed byneutralization of the hydrocarbon portion to yield the alkylarylsulfonate salt, a water-soluble, biodegradable or soft" detergent.

In the first step of the reaction sequence, the normal parafiins in thestraight-run fraction are separated therefrom by contacting the mixturewith pelleted alumino-silicate molecular sieves which selectively sorbthe normal paraffinic components of the mixture and leave a non-sorbedraffinate consisting of isoparalfins and the cyclic hydrocarbons presentin the fraction. For effecting this separation, the straight-runkerosene fraction is poured at room temperature (25 C.) into a verticalcolumn packed with the molecular sieve pellets; the resulting column isft. in length and contains 3.8 ft. of the pellets, each having adimension of approximately one-eighth inch by one-eighth inch. Araffinate effluent from the bottom of the column of molecular sievesconsists of n-paraffin-free hydrocarbons. The normal paraffin componentsof the kerosene fraction (about 37 percent of the total volume ofkerosene) remain within the column, sorbed on the molecular sieveparticles. The residual raffinate retained on the surface of the pelletsis washed from the column by pumping isopentane into the top of thecolumn and draining the effluent from the bottom. Any isopentaneremaining on the pellet surfaces is separated from the recoveredn-paraffin sorbate product by distillation. Raftinate contained in thewash effluent is recovered as bottoms on distillation of the washeffluent.

After completely draining the column of iso-pentane wash, then-paraffins sorbed from the kerosene feed stock are desorbed by fillingthe column with liquid npentane at 25 C., allowing the n-pentane todisplace by the mass action effect the kerosene-derived n-paraffinspresent in the pores of the molecular sieve particles, and after minutesthe liquid surrounding the sorbent particles is drained into adistillation flask. The column is again filled with n-pentane and afterstanding for an additional 10 minutes, the liquid in the column isdrained into a second distillation flask. Distillation of the n-pentanefrom the effluent stream in each case left a residue of kerosenen-paraffins (98.5 percent normal components of C C chain length) in eachflask, 96 percent of the total recovered sorbate being in the firstflask. The resultant n-paraffins are then further fractionated to obtaina C (dodecane) fraction containing, 99.4% dodecane and 0.6 percentisomers.

The recovered C n-paraffin is thereafter dehydrogenated by passing theparaffin in admixture with hydrogen at an 8:1 hydrogen to paraffin moleratio to a small pilot plant reactor maintained at isothermal conditionsof 470 C. and 10 psig. The feedstock charge rate (in terms of liquidhourly space velocity) is 32 volumes of paraffin charge per volume ofcatalyst per hour. The catalyst packed in the pilot plant reactor is anarsenic-containing lithiated platinum catalyst containing, 0.75 wt.platinum on alumina, 0.47 arsenic to platinum mole ratio and 0.5 wt.lithium. The product effluent is cooled and normal gaseous componentsremoved to provide a liquid product containing 11.1 wt. docecene, 87.8wt. dodecane, and small amounts of diolefins and aromatics.

This liquid product containing the C mono-olefin is mixed with 10 molarproportions of benzene to C mono-olefin and the hydrocarbon mixturecooled to 0 C. as hydrofluoric acid of 97.5 percent concentration isadded with stirring, to provide a weight ratio of acid to olefins of1.5. This mixture is maintained and agitated for 1.5 hours, maintaininga temperature of about 0 C. The mixture is then allowed to settle andthe upper hydrocarbon phase is withdrawn and washed with dilute causticand then distilled to remove excess benzene. The remainder consistsessentially of 16.8 wt. dodecylbenzene, 83.1 wt. C n-paraffin and traceamounts of unreacted olefin. A portion of this material is furtherdistilled to remove these paraffins, etc. to produce an essentially puredodecylbenzene.

The remaining liquid product containing the dodecane and dodecylbenzenemixture is placed in an agitated flask maintained at 15 C. by a constanttemperature bath as fuming sulfuric acid containing 20% sulfur trioxideis gradually added over a period of two hours with stirring to provide afinal weight ratio of acid to dodecylbenzene of 1.25. This mixture ismaintained a 15 C. with agitation for an additional 1.5 hours to insureessentially complete sulfonation of the alkylaromatic. The mixture isthen allowed to settle and two separate layers form, a black acid lowerphase and a very light yellow-colored top hydrocarbon phase. The tophydrocarbon phase is passed into an equal volume of water, alsomaintained at 15 C. with the resultant mixture being completelycolorless. The mixture is maintained at 15 C. and neutralized to aphenolphthalein end point with a 10 weight percent aqueous solution ofsodium hydroxide. The mixture is allowed to settle to form an upperhydrocarbon phase and a lower aqueous phase containing the neutralizeddodecylbenzene sulfonate. This lower phase is separated and dried toyield an essentially all white de tergent product essentially free frominorganic salts. A portion of the hydrocarbon phase is also evaporated,leaving little residue, indicating no appreciable amounts ofalkylaromatic sulfonate to be present. The lower acid phase is alsoneutralized and evaporated to dryness to form a dark, discolored solid.This solid is extracted with ethanol, with the ethanol upon evaporationleaving essentially no residue, thus indicating all of the alkylaromaticsulfonate to be in the original hydrocarbon phase present upon thecompletion of the sulfonation reaction.

The dodecylbenzene obtained by the removal of the admixed dodecane wassulfonated in the same manner as the dodecane-dodecylbenzene mixtureexcept that upon completion of the reaction, as single dark-brownsolution resulted which upon neutralization and drying yielded a yellowdodecylbenzene sulfonate-sodium sulfate mixture.

EXAMPLE 11 A run somewhat similar to Example 1 is performed utilizingthe entire C C, n-paraffin mixture. This mixture of homologs isdehydrogenated, the resultant olefins alkylated, the resultant alkylatedbenzene sulfonated and the sulfonated alkylaromatic neutralized in thesame manner as the dodecane-dodecylbenzene mixture of Example I. Theresultant neutralized sulfonate recovered from the hydrocarbon phase ofthe sulfonation reaction is a white, inorganic salt-free detergent ofequivalent quality as that formed in Example 1. The unconvertedparaffins are dried and blended with the G -C paraffin passed to thedehydrogenation reaction.

CONCLUSKONS From the foregoing specification and examples, thebeneficial import of the process of this invention is readily apparentto those trained in the art. This process offers a means of converting C-C n-paraffins and a monocyclic aromatic into an alkylaromatic sulfonatecontaining a C C linear alkyl group without involving the intermediateseparation of the n-paraffin. Further, this process makes possible theproduction of alkylaromatic sulfonates free from inorganic salts, thusalleviating the necessity of extracting such salts from the finalproduct heretofore practiced in the art. Most importantly, this processoffers a means for producing alkylaromatic sulfonates free fromundesirable colorbodies without involving sophisticated bleaching andseparation techniques.

We claim as our invention:

1. A process for producing an alkyl aromatic sulfonate containing a C -Clinear alkyl group which comprises the steps of:

a. dehydrogenating a C C n-paraffin by contacting it with adehydrogenation catalyst to form a C C linear mono-olefin, recoveringfrom the resultant hydrogenation effluent said C C linear monoolefin inadmixture with unreacted C C n-paraffin, said unreacted C C n-paraffinbeing present in an amount of from about 20 to about 96 weight percentof the admixture; b. alkylating a monocyclic aromatic with said C -Clinear monoolefin in admixture with the unreacted C -C nparaffin to forman alkyl aromatic containing a C C linear alkyl group;

c. separating unreacted monocyclic aromatic from the resultant effluentof step (b) which contains said unreacted monocyclic aromatic, C,,--Clinear alkyl aromatic, and C -C n-paraffin;

. sulfonating the alkyl aromatic of step (c) in admixture with the C Cn-paraffin of step (c), with an acidic sulfonating agent selected fromthe group consisting of sulfuric acid and oleum to form an alkylaromatic sulfonic acid, said acidic sulfonating agent being present inan amount in excess of the stochiometric quantity required to sulfonatesaid alkyl aromatic;

. separating the resultant sulfonation mixture into an acid phasecontaining excess acidic sulfonating agent and a hydrocarbon phasecontaining said C C, n-parafiin and said alkyl aromatic sulfonic acid;

f. neutralizing the hydrocarbon phase by admixing that phase with anaqueous solution of a base selected from the group consisting of ammoniaand the hydroxides and carbonates of sodium, potassium, lithium andmagnesium, to form a water soluble neutralized alkyl aromatic sulfonate;

g. forming a hydrocarbon phase containing unreacted (l -C n-paraffin,and an aqueous phase containing water-soluble neutralized aromaticsulfonate;

h. separating the phases formed in step (g);

i. recovering water soluble alkyl aromatic sulfonate from ea u ous hase;nd, j. recycliiig t ieast a porti t m of the separated unreacted C -Cn-parafiin of step (g) to dehydrogenation step (a).

2. The process of claim 1 further characterized in that said monocyclicaromatic is benzene said sulfonating agent is oleum and said hydrocarbonphase is neutralized with an aqueous solution of sodium hydroxide.

3. The process of claim 1 further characterized in that said paraffin isdehydrogenated at dehydrogenating conditions and in contact with acatalytic composite of alumina, from about 0. l% to about 1.5% by weightlithium, from about 0.05% to about 5.0% by weight of a Group VIII noblemetal component and a metallic component selected from the groupconsisting of arsenic, antimony, bismuth, and compounds thereof, inatomic ratio to said Group VIII component of from about 0.20 to about0.50; said dehydrogenation conditions including a temperature of fromabout 400 C. to about 600 C. and a liquid hourly space velocity of atleast 12.0.

2. The process of claim 1 further characterized in that said monocyclicaromatic is benzene said sulfonating agent is oleum and said hydrocarbonphase is neutralized with an aqueous solution of sodium hydroxide. 3.The process of claim 1 further characterized in that said paraffin isdehydrogenated at dehydrogenating conditions and in contact with acatalytic composite of alumina, from about 0.1% to about 1.5% by weightlithium, from about 0.05% to about 5.0% by weight of a Group VIII noblemetal component and a metallic component selected from the groupconsisting of arsenic, antimony, bismuth, and compounds thereof, inatomic ratio to said Group VIII component of from about 0.20 to about0.50; said dehydrogenation conditions including a temperature of fromabout 400* C. to about 600* C. and a liquid hourly space velocity of atleast 12.0.